A web application is an application that is compiled by using a web language and that is constructed based on a standard web technology. Different from a traditional website, a web application emphasizes that a user is allowed to perform various operations rather than simply browse web content, for example, operations of sending an electronic mail (e-mail), hunting for a house, paying a bill, balance transferring, shopping, and sending an invitation. A traditional web, however, is content-oriented and provides convenient browsing and consumption by using static information.
A web application may be classified into the following two representation forms: a packaged web application and a hosted web application. Both source code and data of the hosted web application are stored on a server of a developer, and when releasing a web application by using an application store, the developer submits only a manifest file. When installing a web application from the application store, a client of a user obtains only an icon and a Uniform Resource Locator (URL) web address, and the user directly accesses the server of the developer by using this network address. If a malicious program is introduced when the source code of the web application is changed on the server of the developer, because the network address of the web application remains unchanged, when the user accesses the Web App, the server of the developer is directly linked to. In this way, the malicious program is downloaded to the client of the user, and there is a security risk for the user to access the web application.